1. Field of the Invention
The invention relates to a method for producing organooligosilsesquioxanes from silicates and disiloxane compounds.
2. Description of the Related Art
Organooligosilsesquioxanes are useful as crosslinking agents for silicones and organic polymers.
DE 38 37 397 A1 and also DE 101 56 619 A1 disclose organooligosilsesquioxanes and methods for producing them. In DE 38 37 397 A1 such organooligo-silsesquioxanes are preferably produced by the reaction with a reactant in excess as a solvent for the reaction product.
Furthermore, examples 8 and 9 of DE 38 37 397 describe a production method which, from the start of silicate production to obtaining the pure reaction product, constitutes a 6-step manufacturing process:    first, producing the silicate base by reacting precipitated silica with aqueous tetramethylammonium hydroxide solution;    second, concentrating the reaction mixture and crystallizing the tetramethylammonium silicate product at 4° C.;    third, reacting tetramethylammonium silicate with a reactant used in excess and acting as solvent for the organooligosilsesquioxane;    fourth, phase separating and washing the organic phase until neutral;    fifth, evaporating the washed neutral reaction mixture to dryness; and    sixth, recrystallizing the residue from an alcohol.
Thus, DE 38 37 397 A1 describes a production method having unavoidably high cost requirements and relatively poor yields (of 60-70%) in order that high-purity organooligosilsesquioxanes may be produced.